#include <stdio.h>
#include <string.h>
union Num
{
    int a; 
    char b[32];
};
union Sex
{
    char a;
    char b[4];
    int c;
};
struct Student
{
    union Num num;//32
    char name[32];//32
    union Sex sex;//4
};

int main()
{
    struct Student s;
    s.num.a = 1001;
    strcpy(s.num.b,"1001");

    printf("num = %d\n", s.num.a);
    printf("num = %s\n", s.num.b);
}
